tunneling:
ovpn relevant fixes:

    -up /etc/openvpn/update-resolv-conf
    -down /etc/openvpn/update-resolv-conf
    +#up /etc/openvpn/update-resolv-conf
    +#down /etc/openvpn/update-resolv-conf

    +route-nopull
    -redirect-gateway $def1
    -dev tun
    +dev $(your interfacename here)
    +dev-type tun

    -auth-user-pass
    +auth-user-pass $(your openvpn user_pass_file here)

normal firewall stuff:
    shorewall:
    in /etc/shorewall/interfaces
    +loc     $(interfacename)           detect          tcpflags,nosmurfs,routefilter,logmartians

ip+iptables
    iptables --table nat -A POSTROUTING -o $(your interfacename here) -j MASQUERADE
    ip route add table $(interfacename) via $(route -n | grep $(interfacename) | grep 0.0.0.0 | awk '{print $1}') dev $(interfacename)
    ip rule add $(your rule spec here) table $(interfacename)